Of the two lines of pigment cells in the eye only the pigmented epithelial cells have been extensively studied. All studies using embryonic eyes were done on pigmented epithelial cells because, unlike stromal melanocytes, they develop early in fetal life. Furthermore, since the stromal pigment cells from normal cells from normal eyes are difficult to maintain in culture, they were rarely studied. Anatomical and functional considerations suggest that stromal pigment cells have activities other than light screening. We propose to develop an in vitro model to study how stromal pigment cells of the rhesus eye grow and differentiate, how they interact with the nonpigment-forming cells of the uvea stroma, and how they function in health and disease.